The present invention relates to ignition systems for internal combustion engines and in particular to novel ignition coil structure which eliminates high voltage distribution in the system, promotes easier maintenance and improved safety and reliability, minimizes radio interference and reduces exhaust emissions especially in older vehicles.
The secondary, or high voltage, portions of engine spark ignition systems have experienced little fundamental change since the days of Charles Kettering. Although advances in semiconductor technology have recently been widely applied to improve performance and reduce maintenance of the primary, or low voltage, portions of ignition systems, the highly vulnerable rotor, distributor cap, and high voltage harness remain in widespread use on multicylinder production gasoline automobile engines.
While these high voltage distribution systems may be made to function satisfactorily when new, such is typically not the case as the automobile becomes older. In the high temperature environment under the automobile hood, organic rubber parts rapidly age and crack. Moisture and salt spray together with under hood dirt provide conductive flashover and leakage paths resulting in missing, crossfiring, and difficult starting. The multiple conductors of the high voltage harness provide excellent antennae for conducting and radiating radio frequency noise produced by the ignition system. The commutating spark between the distributor rotor and terminals of the distributor cap has been identified in reliable scientific studies as the primary source of ignition in under hood fires which may follow accidents or other gasoline leakage under the hood. The interior of the distributor cap requires ventilation to the atmosphere to prevent pressure build up and corrosion; while some distributors have been produced which are vented through a Davey Screen, these are not in widespread use.
The present invention is directed to a novel ignition system which substantially alleviates, or eliminates entirely, the aforementioned and other problems associated with currently prevailing ignition systems which use a mechanical distributor and a high voltage harness for supplying energy to the spark plug. The advantages resulting from the present invention include: a substantial reduction of ignition maintenance cost; a substantial reduction of radio interference; improved reliability of ignition; and reduction of automobile exhaust hydrocarbon and carbon monoxide emissions particularly in automobiles in advanced age and use. Furthermore, the present invention can render feasible marine ignition systems capable of operation for significant periods of time while covered with sea water as well as ignition systems capable of operation in combustible atmospheres without danger of fire or explosion. Novel aspects of the disclosure include novel ignition coil structure, novel ignition structure, a novel method for making an ignition coil, a novel means for grounding the primary winding of the ignition coil, and a novel means for assuring a tight fit between the insulating member which surrounds the ignition coil and the spark plug which includes a filtered vent passage for allowing egress of air trapped between the insulating member and the spark plug.
Additional advantages and features of the invention, along with those already mentioned, will be seen in the ensuing description and claims which are to be taken in conjunction with the accompanying drawings.